In a device such as a terminal device, in one technology, various techniques are proposed to avoid wasteful power consumption. For example, in some cases, users activate the terminal devices, but leave them untouched without use. There are proposals for a terminal device such that an unused state is detected by the terminal device so that the terminal device itself can be shifted to a power-saving mode.
In other words, a sensor such as an infrared sensor for detecting whether or not a user is present is provided so that the terminal device determines whether or not the user leaves the seat and is away from the seat based on the detection signal of this sensor. When such a state of absence is detected, a method of processing to power off the screen of the display unit of the terminal device is proposed.
In addition, in a method of detecting whether or not a user is present based on whether or not the sensor value of the infrared sensor, for example, exceeds a threshold, even if the user is not present in fact, a wrong determination might be made that the user is present, when the sensor value exceeds the threshold according to a change in the temperature environment.
For this reason, there is a proposal of using an infrared detection element that outputs an absolute sensing signal. By use of the absolute sensing signal and differential sensing signal output from the infrared detection element, entering or exiting from the room is determined so as to avoid a wrong determination caused by a change in the temperature environment (for example, see PLT 1).